Reduced levels of S-nitrosothiols in plasma of patients with systemic sclerosis and Raynaud's phenomenon

Evaluation of renal damage in a bleomycin-induced murine model of systemic sclerosis

Objectives

Systemic sclerosis (SSc) is an autoimmune disease of unknown etiology with a high mortality rate. Renal crisis has been reported as one of the predictors of early mortality in these patients. The present study was performed to evaluate bleomycin-induced SSc using an osmotic minipump as a possible model for the analysis of renal damage in SSc.

Materials and Methods

Male CD1 mice were implanted with osmotic minipumps loaded with saline or bleomycin and sacrificed at 6 and 14 days. Histopathological analysis was performed through hematoxylin and eosin (H&E) and Masson's trichrome staining. The expression of endothelin 1 (ET-1), inducible nitric oxide synthase (iNOS), transforming growth factor β (TGF-β), and 8-hydroxy-2-deoxyguanosine (8-OHdG) was also evaluated by immunohistochemistry.

Results

The administration of bleomycin induced a decrease in the length of Bowman's space (3.6 μm, P<0.001); an increase in collagen deposition (14.6%, P<0.0001); and an increase in the expression of ET-1 (7.5%, P<0.0001), iNOS (10.8%, P<0.0001), 8-OHdG (161 nuclei, P<0.0001), and TGF-β (2.4% µm, P<0.0001) on Day 6. On Day 14, a decrease in the length of Bowman's space (2.6 μm, P<0.0001); increased collagen deposition (13.4%, P<0.0001); and increased expression of ET-1 (2.7%, P<0.001), iNOS (10.1%, P<0.0001), 8-OHdG (133 nuclei, P<0.001), and TGF-β (0.6%, P<0.0001) were also observed.

Conclusion

Systemic administration of bleomycin via an osmotic minipump produces histopathological changes in the kidneys, similar to kidney damage in SSc. Therefore, this model would allow the study of molecular alterations associated with SSc-related renal damage.

[Functional vascular acrosyndromes]

Vascular acrosyndromes are characterized by sparse, uniform clinical manifestations and a variety of possible pathomechanisms. The present article focuses on the functional entities. Raynaud phenomenon is based on cold- or stress-induced vasospasms of acral arteries. It is defined by the color changes of the skin, in the typical case white-blue-red (tricolore). The long fingers are most commonly affected. The etiology is unknown, and the pathophysiology is poorly understood. A distinction is made between primary and a secondary Raynaud phenomenon. The most important underlying diseases include collagenosis, primarily systemic sclerosis, and malignancies; furthermore, medications and drugs may promote vasospasm. Treatment is aimed at preventing or breaking the vasospasm, but has been only partially effective in doing so. Acrocyanosis is a vasospastic dystonic acral disorder that results in permanent reddish-livid discoloration, especially of the hands and feet. Secondary forms occur in collagenosis, malignancies, and myelodysplastic syndromes. The etiology and pathophysiology are virtually unknown. Targeted pharmacological intervention is not possible. Unlike all other vascular acrosyndromes, erythromelalgia is characterized by hyperemia. The primary form is a genetic sodium channelopathy, while secondary forms include malignancies, connective tissue diseases, and myelodysplastic syndromes. The symptoms are often distressing and disabling. Therapy requires a multimodal approach that includes both nonpharmacological and pharmacological strategies. Close interdisciplinary collaboration is essential for the management of this disease.

Enzyme Mimics for the Catalytic Generation of Nitric Oxide from Endogenous Prodrugs

The highly diverse biological roles of nitric oxide (NO) in both physiological and pathophysiological processes have prompted great interest in the use of NO as a therapeutic agent in various biomedical applications. NO can exert either protective or deleterious effects depending on its concentration and the location where it is delivered or generated. This double-edged attribute, together with the short half-life of NO in biological systems, poses a major challenge to the realization of the full therapeutic potential of this molecule. Controlled release strategies show an admirable degree of precision with regard to the spatiotemporal dosing of NO but are disadvantaged by the finite NO deliverable payload. In turn, enzyme-prodrug therapy techniques afford enhanced deliverable payload but are troubled by the inherent low stability of natural enzymes, as well as the requirement to control pharmacokinetics for the exogenous prodrugs. The past decade has seen the advent of a new paradigm in controlled delivery of NO, namely localized bioconversion of the endogenous prodrugs of NO, specifically by enzyme mimics. These early developments are presented, successes of this strategy are highlighted, and possible future work on this avenue of research is critically discussed.

Oxidative stress in the pathogenesis of systemic scleroderma: An overview

Systemic sclerosis (SSc) is a rare disorder of the connective tissue characterized by fibrosis of the skin, skeletal muscles and visceral organs. Additional manifestations include activation of the immune system and vascular injury. SSc causes disability and death as the result of end‐stage organ failure. Two clinical subsets of the SSc are accepted: limited cutaneous SSc (lc‐SSc) and diffuse cutaneous SSc (dc‐SSc). At present, the aetiology and pathogenesis of SSc remain obscure, and consequently, disease outcome is unpredictable. Numerous studies suggest that reactive oxidizing species (ROS) play an important role in the pathogenesis of scleroderma. Over the years, several reports have supported this hypothesis for both lc‐SSc and dc‐SSc, although the specific role of oxidative stress in the pathogenesis of vascular injury and fibrosis remains to be clarified. The aim of the present review was to report and comment the recent findings regarding the involvement and role of oxidative stress in SSc pathogenesis. Biomarkers proving the link between ROS and the main pathological features of SSc have been summarized.

Raynaud's phenomenon: Current concepts

Raynaud's phenomenon (RP) is a transient, acral, vasospastic phenomenon that manifests with characteristic color changes. This vasospasm, classically triggered by cold temperatures, may also be driven by shifts in temperature, climate, or emotional state. Primary RP (PRP) is a common condition without severe sequelae. Secondary RP (SRP), which may be driven by vascular, autoimmune, hematologic, or endocrine etiologies, can result in digital ulceration, irreversible ischemia and necrosis, and secondary infection. This review delineates the clinical manifestations of both primary and secondary RP, as well as the current understanding of RP epidemiology and pathogenesis. Proper examination, including nailfold capillary microscopy, and laboratory workup for secondary causes of RP are also discussed. The traditional armamentarium of therapies used for RP, as well as newer medical and surgical options, is also summarized with particular regard to the clinical evidence for their efficacy.

Therapeutic implications from the pathogenesis of Raynaud's phenomenon

INTRODUCTION

Raynaud's phenomenon (RP) can be either primary (idiopathic) or secondary to a number of different diseases/conditions, when vasopasm can be superimposed upon structural vascular abnormality or a hyperviscosity state and may then lead to severe ischaemia with tissue damage. Treatment must be tailored to the individual. Areas covered: This review discusses how increased understanding of the pathogenesis of RP has driven and is driving new approaches to therapy, and how we are now better able to predict which patients presenting with RP are likely to have an underlying disease requiring specific intervention. Medline searches (1946 to August 2016) were conducted for 'Raynaud's' in combination with relevant terms including different drugs. All papers identified were English language, with abstracts. Expert commentary: Randomised controlled trials of RP present particular challenges. The major aim must continue to be development of safe, effective treatments for patients across the spectrum of RP.

Raynaud's Phenomenon: A Brief Review of the Underlying Mechanisms

Raynaud’s phenomenon (RP) is characterized by exaggerated cold-induced vasoconstriction. This augmented vasoconstriction occurs by virtue of a reflex response to cooling via the sympathetic nervous system as well as by local activation of α_2C adrenoceptors (α_2C-AR). In a cold-initiated, mitochondrion-mediated mechanism involving reactive oxygen species and the Rho/ROCK pathway, cytoskeletal rearrangement in vascular smooth muscle cells orchestrates the translocation of α_2C-AR to the cell membrane, where this receptor readily interacts with its ligand. Different parameters are involved in this spatial and functional rescue of α_2C-AR. Of notable relevance is the female hormone, 17β-estradiol, or estrogen. This is consistent with the high prevalence of RP in premenopausal women compared to age-matched males. In addition to dissecting the role of these various players, the contribution of pollution as well as genetic background to the onset and prevalence of RP are also discussed. Different therapeutic approaches employed as treatment modalities for this disease are also highlighted and analyzed. The lack of an appropriate animal model for RP mandates that more efforts be undertaken in order to better understand and eventually treat this disease. Although several lines of treatment are utilized, it is important to note that precaution is often effective in reducing severity or frequency of RP attacks.

Nailfold capillaroscopy assessment of microcirculation abnormalities and endothelial dysfunction in children with primary or secondary Raynaud syndrome

Raynaud syndrome (RS) manifests as episodes of transient spasms of peripheral blood vessels, most often in response to cold. The reason of that symptom (primary RS (pRS)) usually cannot be found but may be accompanied by some autoimmune diseases (secondary RS (sRS)). In this study, we assessed microcapillary status and serum concentrations of chosen cytokines, adhesive molecules, and nitric oxide (NO) in patients with pRS and sRS in comparison with healthy children. Eighty-six patients with RS were enrolled into the study, including 52 with pRS and 34 with sRS. The control group consisted of 29 healthy children. A decrease in myorelaxative and anticoagulant abilities was observed, with simultaneous prevalence of vasopressor substances and procoagulative activity. Therefore, several important factors such as endothelin-1 (ET-1), E-selectin (E-sel), interleukin-18 (IL-18), and nitrogen oxide (NO) were also analyzed. Two types of capillaroscopy status were determined: normal and microangiopathic. There was a significant relationship between presence of microangiopathy and higher serum ET-1 (p = 0.018) and E-sel (p = 0.021) levels. Similarly, we have found a correlation between presence of ANA and higher ET-1 (p = 0.005), but not E-sel (p = 0.241). In patients with pRS, we found significant relationship between ANA and higher ET-1 (p = 0.008). No such relations were observed in sRS patients. Our data indicates that external factor-induced vasoconstrictive effects dominated in pRS, whereas in sRS in the course of connective tissue diseases, it was accompanied by coexistent vasodilation due to endothelial dysfunction. The latter phenomenon is at least partially dependent on insufficient NO release.